SOURCE: Duke University

DATE: March 26, 2019

SNIP: Older power plants with once-through cooling systems generate about a third of all U.S. electricity, but their future generating capacity will be undercut by droughts and rising water temperatures linked to climate change. These impacts would be exacerbated by environmental regulations that limit water use.

The new study shows that if surface waters warm 3 degrees Centigrade and river flows drop 20 percent — both of which are probable by the end of the century — drought-related impacts will account for about 20 percent of all capacity reductions at thermoelectric power plants with once-through, or open-loop, cooling systems. These reductions include capacity curtailments or shutdowns that could occur when local surface water levels drop below a plant’s intake structures.

Environmental regulations that govern a plant’s water use and the maximum temperature of used cooling water it can discharge back into rivers or lakes will account for much of the remaining 80 percent of future shutdowns and capacity cuts, Pratson said.

Thermoelectric power plants use steam-driven turbines to generate their energy. Once the steam has passed through the turbines it must be cooled down. Once-through systems do this by drawing in cold water from nearby rivers or lakes, circulating it through pipes to absorb the steam’s heat, and discharging the heated water back into the river or lake.